The present invention is directed to bicycles and, more particularly, to an apparatus for fine tuning a bicycle derailleur position.
Bicycle transmissions that comprise front and rear derailleurs are well known. The front derailleur shifts a chain among a plurality of front sprockets that are coaxially mounted to the pedal crank shaft, and the rear derailleur shifts the chain among a plurality of rear sprockets that are coaxially mounted to the rear wheel. It is also known to use electric motors to operate the front and rear derailleurs, wherein operating a button or lever on a shift control device mounted to the bicycle handlebar controls the motors. Such a system is shown in Japanese Patent Application No. 2002-87371.
The chain is oriented in very extreme angles when it engages the innermost front sprocket in combination with the outermost rear sprocket and when it engages the outermost front sprocket in combination with the innermost rear sprocket. Depending upon the design of the bicycle frame, such extreme angles may cause the chain to rub against the front derailleur cage. Even when the front derailleur is initially installed in a proper position, the derailleur may subsequently move over time, thereby again causing the chain to rub against the derailleur cage in such situations. Such contact causes noise, greater pedaling resistance, and excessive wear on the derailleur cage.